1. Field of the Invention
The present invention relates to a web winding apparatus including a plurality of spools rotatably disposed in an axial array on a takeup shaft, which can be rotated to wind up webs on the respective spools.
2. Description of the Related Art
There are known rewinders for automatically winding an elongate web such as an elongate film, an elongate sheet of light shielding paper, or the like on a spool, and slitters for slitting, i.e. longitudinally cutting a wide stock web into elongate webs each having a predetermined width and automatically winding the webs on respective spools. Those rewinders and slitters incorporate a web winding apparatus having a plurality of spools that are rotatable to wind respective elongate webs therearound.
One web winding apparatus of the type described above has a sheet takeup shaft assembly as disclosed in Japanese Laid-Open Patent Publication No. 2000-16642, for example. As shown in FIG. 7 of the accompanying drawings, the disclosed sheet takeup shaft assembly has a plurality of spool holders 2 disposed in an axial array on a shaft 1 which supports spacers 3 on respective opposite ends thereof. The spool holders 2 are fixedly held on the shaft 1 by a nut 4 which is threaded into one end of the shaft 1. Each of the spool holders 2 has a fixed member 5 and a movable member 6 slidably fitted over the fixed member 5. A piston 7 is movably mounted in the fixed member 5, providing a cylinder 8.
The shaft 1 has an air supply passage 9 defined centrally therein which is held in communication with an air inlet path 10 defined axially in an outer circumferential surface of the shaft 1. The cylinders 8 of the respective spool holders 2 communicate with the air inlet path 10.
Spools 11 are disposed in the respective spool holders 2. When air under pressure is supplied from the air supply passage 9, the air under pressure flows from the air inlet path 10 into the cylinders 8 of the respective spool holders 2. The pressure buildup in the cylinders 8 displaces the pistons 7 into abutment against the movable members 6, which move toward one end of each spool 11. The spools 11 are now held in position by the movable members 6 and the fixed members 5 that are positioned on the other ends of the spools 11.
Then, the leading ends of elongate webs (not shown) are attached to the respective outer circumferential surfaces of the spools 11. When the spools 11 are rotated, the spool holders 2 are also rotated in unison with the spools 11. The spools 11 are sandwiched between the vertical surfaces of the fixed members 5 and the movable members 6. Slippage occurs on the opposite ends of the spools 11 due to the resistance posed by the webs against the rotation of the spools 11, and the webs are wound on the spools 11 under tension.
Since the spools 11 are axially arrayed on the shaft 1, the webs can be wound on the respective spools 11 under constant tension without causing an error with respect to the dimension of wound layers of the webs.
However, in the conventional sheet takeup shaft assembly, the plural spool holders 2 are mounted on the shaft 1 and incorporate the respective cylinders 8 which have the pistons 7 for moving the movable members 6 toward and away from the respective fixed members 5. Therefore, the spool holders 2 are considerably complex in structure, making the overall sheet takeup shaft assembly including the spool holders 2 highly costly to manufacture and hence uneconomical.